1. Field of the Invention
The present invention relates, in general, to an ammunition round for use with rifled or non-rifled barrels, and, more particularly, to a hollow slug having a circumferential recess configured to engage a projection on a slug casing.
2. Description of the Related Art
Regardless of whether used in hunting, military, or law enforcement applications, a slug is a type of an ammunition round typically used with a shotgun. The slug is a heavy projectile, typically made from lead, copper-covered lead, or other metal, encased in a plastic or metal casing. The slug projectile and its propellant are encased in a single casing. The external dimension of a slug casing and/or the slug projectile is dimensioned such that the outer dimension of the slug casing and/or the slug projectile is nominally the same as the internal diameter of the rifle or gun barrel. This is an important design consideration in order to create a tight seal between the slug and the barrel for preventing the escape of gas generated by the propellant once the gun is fired. Most conventional slugs are specifically designed for use with either rifled or non-rifled barrels. Slugs for use in rifled barrels usually have a solid core, while slugs for use with non-rifled barrels may have a solid or hollow core.
Certain slug designs utilized with rifled barrels may have a hollow projectile that has a pit or hollowed-out shape at its tip. Generally, these types of slugs are intended to cause the slug to fragment upon impact, such that most of the kinetic energy of the slug is expended upon impact. When a slug of this kind strikes a target, the slug widens at its tip to increase the frontal surface area of the slug and limit its depth of penetration. Other collapsible slug designs have cutout portions which collapse and expand once the slug strikes a target. These slugs feature openings that have portions of the core extruded out and have a tip portion that is prevented from rotational or longitudinal movement until the inner part of the tip near the extruded portions is weakened upon impact to allow for a “mushrooming” effect.
In general, most slugs are encased inside a plastic casing that is filled with a propellant, such as gun powder. The casing is typically a thin-walled cylindrical structure with an open top end and a closed bottom end. The propellant is ignited by a primer housed at the base of the casing that is acted upon by a firing pin. One or more additional materials, such as a gas seal, sabot, concertina pressure wad, or spacer wad, are packed between the propellant and the slug. Typically, this additional material takes up volume within the casing, seals the bore, and reduces the friction between the slug and the barrel as the slug travels through the barrel upon firing. The slug is firmly retained within the casing until the propellant is ignited. The buildup of pressure inside the casing causes the slug to be released and fired from the barrel.
Regardless of whether the firing weapon has a rifled or non-rifled barrel, an important design consideration in making slugs is ensuring that the slug casing opens up to release the slug during firing. Cold weather, in particular, exacerbates the problem. In very cold temperatures, the common practice of using a Star Crimp or a Roll Crimp to hold slugs in place often causes the top end of the casing to split or become separated from the cylindrical sidewall causing erratic performance and accuracy.
It will readily be appreciated by those skilled in the art that the problems associated with existing slug designs call for a solution that is not readily available within the prior art.